First released in 2014, Swift has soared in popularity among developers because of its speed and reliability, among other benefits. And with every release, the language gets faster, which in turn delivers a better user experience. However, it is likely that you will experience performance issues every now and then. In such instances, these tips can come in handy to boost code performance of Swift.

Set the optimization level in build settings

The first step towards boosting your swift code performance is to let the Xcode optimize itself. The Xcode compiler knows when to overlook function results that have no impact or call directly to methods that weren’t sub-classed. Just look for the ‘optimization level’ settings under the ‘Swift Compiler –Code Generation’ section in your build settings, and you will find three options;

• No optimization;
• Optimization for speed;
• Optimization for size.

Select ‘optimization for speed’ for release builds and ‘optimization for size’ for debug.

Use ‘final’ and ‘private’ for methods and classes

Swift Optimization manages and controls different things, and one of them is a direct or indirect call to methods. For proper functionality, Swift uses Dynamic Dispatch to decide the right method to invoke whenever a message is sent to an object using a Virtual Table. Searching for a virtual table for an address when an object is requested to return to the method address is not a straightforward process, affecting performance. You can fix this problem by adding the attribute ‘final’ to the start method or even the whole class to ensure that the call to the method is direct.

Avoid ‘print’ in release builds

We all know that printing to console is a great debugging strategy, but many developers tend to leave the ‘print’ commands floating around in the code. The problem is that the action negatively affects performance as tests with a ‘print’ call ran 1600 slower. Your best bet is to avoid calling to print, and to do this, you can simply embed it with some class with a MACRO, so it doesn’t slip your mind again.

Use a linked list instead of an array

Many developers love to use Arrays, but the problem is that they require a lot of performance optimization. A more efficient alternative is linked lists since it is quite easy to insert an item into their middle because they point to each other. All you need to do is to make sure they are correctly aligned, and you’re done. The only time you may need to use Arrays is when you have to sort or do a lookup.

Limit protocols to class only if possible

Last but not least, try as much as you can to use protocols only for classes. The compiler optimizes the ARC (Reference Counting) when your protocol is only for classes, and this can make your code run faster.

Conclusion

When next you encounter some performance issues, and it seems the different app architecture techniques you know aren’t working, using the tips above can help improve swift engine for maximum speed. Want us to check your iOS app to make it AppStore ready? Contact us now!